Muffle and like furnace



Nov. 23, 1937.

H. w. SPENCER ET AL MUFFLE AND LIKE FURNACE Filed Oct. 8, 1935 2 Sheets-Sheet 1 aji /A/ ven far&

Nov. 23, 1937.

H. w. SPENCER El' AL MUFF'LE AND LIKE FURNAC Filed Oct. 8, 1935 2 Sheets-Sheet 2 Patented Nov. 23, 1937 UNITED STATES MUFFLE AND LIKE FURNACE Henry Wilmot Spencer, Roehampton Lane, London, and Leonard Sherrington Davis, Bexley Heath, England Application 'October 8, 1935, Serial No. 44,096 In Great Britain October 9, 1934 19 Claims.

This invention relates to muflleand like furnaces in which the products of combustion are excluded from the work under treatment by the provision of an inner refractory chamber or muflie around which the products of combustion are circulated. A

With the exclusion of mufiles of the smaller szes which are formed in one piece, this type of furnace sufiers from the objections that it is diflicult to secure the necessary requirement of relatively thin walls and roof or arch with meohanical strength and to maintain the joints of the building units in a gastight condition. Repairs are often difficult and comparatively costly to effect, usually necessitating a substantial dismantling of the furnace and, furthermore. existing types of constructons do not lend themselves to uniform and controllable heating.

Most of the disadvantages in known constructions are due to the necessity of incorpcrating a muiile roof of Sprung construction. The disadvantages of this are well known in ordinary fur; nace constructions but the objections are of greater consequence when a Sprung arch is applied to a muifle as owing to the comparatively thin material which must be employed trouble is experienced in affording adequate support to the side walls due to the thrust of the arch. Even when this is accomplished the life of the muflle may be reduced owing to the compressive stresses present in the muffle. By means of the present invention each individual unit of the muflle is free from stresses induced by adjacent blocks and tlre side units of the muiiie are relievedby thrusts from the arch or roof.

An object of the present invention is to provide a muiile furnace construction adapted to avoid the above objections and to aiford a muifle which not only may be readily repaired or renewed but one which is adequately strong and gastight under ordinary working conditions.

A further object of the'invention is to provide a furnace construction which is capable of more fiexible operation and in which the temperature conditions within the mufiie are susceptible of considerable control.

The invention comprises the provision of suspended furnace arch and wall refractory elements upon the arch elements of which are suspended tiles or units and to the wall elements of which tiles or units are keyed to form the muflle and affording passageways through which the products of combustion are intended to circulate.

The invention also consists in a mufiie arch comprising refractory tiles or units suspended or hung from the refractory elements of a. suspended furnace arch and afiording passageways through which products of combustion circulate.

A feature of theinvention lies in the formation of the tiles with parts or webs carrying the 5 suspension or keying`means and also forming sides of the passages through which the prodi ucts of combustion circulate.

It is preferred to combine the above muflle construction with the jacketed Suspended arch and wall structure forming the subject of our British Patent application No. 28,908 of 1934 and accordingly afurther feature of the invention comj prises the provi'sion of an outer jacketing housingior the Suspended arch and walls carrying 15 the Suspended muflie units of the character indicated and the mechanical circulation of air through the jacket for controlling the temperatu'e conditions and so` as to make the heated air available for combustion or otherwise to avoid heat losses.

It is to be understood that the expression suspended wall element" used herein means a refractory element s forming part of the furnace wall as distinct from the arch and supported by means such as a hook or bracket so that the lower blocks do not sustain the cumulative weight of those above. p

In the accompanying drawingsz- Figura 1 is aside elevation partly in section of a mufile furnace ccnstructed according to the invention and in combination with an air jacketed Suspended roof and wall construction according to our British specification numbered as above.

.Figura 2 is atransverse-sectional end elevation taken on the' lines A-A of Figura 1.

Figure 3 is a fragmentary sectional plan on the lines B-B of Figura 2, and

Figures 4, 5, and 6 are sectional detail views of modified forms of tiles and joints for suspending the muflie arch or wall tiles.

In carrying the invention into effect according to one convenient mode as illustrated in Figures 1, 2, and 3, a framework comprising upright g'lrders I and horizontal transverse bearers 2 is provided with an outer wall of insulating blocks or lagging 3. The uprights l are provided with angle brackets`4' on which refractory blocks 5 forming the Suspended wall of the furnace are hung in known manner. The roof or arch of the furnace isfformed by rows of refractory blocks E the `rear or upper sides of which are provided with recesses in which longitudinal bars i 'i are engaged` These bars are slung upon hook i members 8 which in turn are carried by longltudinal rods 9 resting on the bearers 2. The Suspended walls and arch are -erected as will be seen in spaced relationship with the insulating outer wall 3 afiording an air jacket A around the walls and over the roof or arch. The jacket space may, if desired, be provided with bales for directing the course of the air current.

A fan or blower ID adapted to be driven at various speeds forces air into the jacket through the branched conduit I I. This air clrculates over the roof and down the walls and is preferably supplied through branches l2 to burners 13 for combustion purposes.

Instead of driving the fan or blower at various speeds the quantity of air passing through the jacket may be regulated by dampers or valves.

The base of the furnace is provided with chambers |4 divided from one another by partitions, the chambers being provided with burners located alternately on opposite sides of the furnace. The partitions l4 support the floor forming slabs l5 of the muille or inner chamber !6.

The mufile walls and arch or roof are formed of tile members ll', |8 which are hung from the walls and roof by longitudinally or transversely extending joints. As illustrated the tiles are formed with a facing portion IQ and a rearwardly extending web or webs 20 which terminate rearwardly in a dovetailed (or other) jointing part 2| 'which fits into corresponding recesses in or between the blocks 5 and 6. The web portions 20 position the faing parts or tile fronts !9 in spaced relationship with the faces of the Suspended wall and roof blocks so that passages are formed between the rear of the faces !9 and the front of the blocks 5 and 6, such passages being bounded laterally by the webs 20, thus forming conduits or passages B for the circulation of products of combustion as indicated by the arrows on Figure 2 of the drawings.

The passages formed by the webs provide separate zones for the products of combustion and by the provision of a burner for each pasageway the heating of the furnace can be variably controlled.

The dovetail or keying means for the tile members in the Suspended blocks may be of various forms and the tile members may have a pair of Web parts and keying means so that they are of channel form or they may be of box form with a single keying means.

According to one Construction (see Figure 4) the tiles have face portions !9 with web portions 20at each side. One of these web portions terminates in a wedge piece Zla while the other is provided with a T-head 2lb. The sides of the tile may be provided with grooves and ribs 22, 23, which engage corresponding ribs and grooves on the adjacent tiles for prevention of the passage of products of combustion. The suspension blocks such as the arch blocks 6 shown in Figure 4 have their sides recessed as at Ga and Gb to receive and correspond with the portions 2l-a and 2lb. According to Figure 5 the parts I 9 have webs 20 with angled or fianged pieces 2la and 2lb formed at different distances from the face portions |9 of the tiles. In this case the suspension blocks are formed with correspcnding recesses Ba and Gb.

In Figure 6 a hollow tile member is shown. This c mprises a face portion !9, side portions 20 and a T-piece 2|c extending from the back por-- tion |9-a of the tile and adapted to engage in T- slots in the arch or wall Suspended blocks. In

this form the passages B are totally enclosed in the tile members themselves instead of being formed between the Suspended blocks and the rear face of the tiles. This figure also exemplifies the provision of a plurality of gastight jointing means as indicated by the grooves 22 and ribs 23 formed on each of the side faces of the tiles.

The muffle tiles are formed of silicon carbide, fused alumina or other refractory material, and the design, shape and sizes may 'be modified to suit the requirement of any particular furnace design. Any-suitable known jointing or filling material may be used for bedding the tiles. Furthermore, tiles orunits of special shape may be formed for completing a row or otherwise to fit corners or other localities.

Having now described our invention what we claim as new and deslre to secure by Letters Patent is:

1. A muffle furnace Construction comprising Suspended arch refractory elements and mule elements Suspended from the arch elements to form a continuous muffie wall and affording passageways through which the products of combustion are intended to circulate.

2. A muflle furnace Construction comprising Suspended arch refractory elements and muflle elements having a. keying connection with said arch elements and cooperatng to form a continuous muflle wall with passageways for the products of combustion.

3. A muflle furnace Construction comprising Suspended arch refractory elements and muffie elements Suspended from the arch elements in Contacting relation to form the mule wall and affording passageways for the products of combustion.

4. A mufile furnace Construction comprising Suspended arch refractory elements and muflle elements having a keying connection with the arch elements, sa-id muie elements forming a continuous muflie wall surface and passageways for the products of combustion, the inner surface of the Suspended arch constituting one side of said passageways.

5. A mufile furnace Construction comprising Suspended wall refractory elements and mufile elements having a keying connection with said wall elements and cooperatng to form a continuous mule wall with passageways for the products of combustion.

6. A mufile furnace Construction comprising Suspended wall refractory elements and mufile elements having a keying connection with said wall elements, said muflle elements forming a continuous muflie wall surface and passageways for the products of combustion, the inner surface of the Suspended wall constituting one side of said passageways. i

7. A muflle arch comprising Suspended refractory elements and a mufiie wall composed of contiguous elements affording a continuous wall surface and having rearwardly directed parts in keying suspension connection with the Suspended elements and forming passageways for the products of combustion.

8. A muffle arch comprising Suspended refracwardly directed parts of keying form engaging a keying connection with the Suspended elements.

. muflie elements being formed to define a passage-- 10. A muflie arch Construction comprising suspended refractory arch elements and muflle elements Suspended from said arch elements to form a continuous muflle wall surface, each of said way for the products of combustion.

11. A muffle furnace construction comprising Suspended arch refractory elements, muflle-elements Suspended from said arch elements to form 'a continuous mufile wall surface and afiording passageways for the products of combustion, and means forming an air jacket outside the suspended arch throughlwhich air may be circulated. 12. A muflle furnace Construction comprising Suspended arch and wall' refractory elements, mufile elements united by keying connections to said arch or wall elements and afiording passageways for the products of combustion, and means forming an air jacket outside the Suspended arch and walls through which air may be circulated.

13. A muflle furnace Construction comprising Suspended arch refracto'y elements, mufile elements Suspended from said arch elements to form a continuous muflle wall surface and afiording separate passageways for the products of combustion, separate base compartments communicating with said passageways, and burners for said base compartments whereby controllable zones are provided` for the products of combustion. a

14. A mufll'e. furnace construction comprising Suspended wall refractory elements, muille ele'- ments united bykeying connections to said wall elements and afording passageways for the products of combustion, separate base compartments communicating with said passageways, and burners for said base compartments whereby controllable zones are provided for the products of combustion.

15. A muflle furnace construction 'comprising Suspended arch refractory elements and muiile elements Suspended therefrom, said muflle elements having rearwardly extending webs formlng between them a passageway for products of combustion and said' webs being formed with dovetail suspension means for engagement with said arch elements.

16. A muflle furnace Construction comprising.

`Suspended wall refractory elements and muflle elements having'a keying connection with said wall elements, said muflle elements having rear'- wardly extending webs forming between them a passagway for products of combustion and said webs being formed with dovetail keying means for keying connection with said wall elements.

17. A mufile furnace Construction comprising Suspended arch refractory elements and mulile elements Suspended therefrom to form a continuous mufile wall, said mufiie elements comprising a relatively thin tile of box section adapted to form a passageway for the products of combustion and having rearwardly extending means forming a suspension connection with the arch elements. v

18. A muflle furnace Construction comprising Suspended wall refractory elements and mule elements arranged to form a continuous muffie wall and having a keying connection with said wall elements, said mufie elements comprising a relatively thin tile of box section adapted to form a passageway for the products of combustion and having rearwardly extending means forming a keying connection with the wall elements.

19. A refractory element for a muflie furnace comprising a relatively thin tile having rearwardly extending webs forming between them a passageway adapted to convey the products of combustion for heating the muflle, said 'webs being of different but complementary shape and adapted, when the webs of adjacent elements are placed in contiguity, to afiord dovetail suspension means for the refractory elements.

H. WILMOT SPENCER. LEONARD SHERRINGTON DAVIS. 

